


My Assassin Academia

by CanineR7A7



Category: Assassination Classroom, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Alternate Universe - Mineta Minoru Doesn't Exist, Because Nagisa & Shoto exist, Check the chapter notes for information on the Assassination Classroom characters’ quirks, Child abuse will be mentioned, Hiromi Shiota can rot in hell, I had to fit Nagisa into 1-A somehow, I’ll add more tags when they become relevant, I’ve had this crossover idea for a while, I’ve tagged all members of 1-A & 3-E but I probably won’t use all of them, Korosensei was a villain, Nagisa is in the Dekusquad, Nagisa lives with his father, Other, Shiota Nagisa-centric, Yaoyorozu Momo is in the Dekusquad, but not really, everyone in 3-E has a quirk, though I probably wouldn’t have included the grape stain either way
Language: English
Status: In-Progress
Published: 2020-10-06
Updated: 2020-10-06
Packaged: 2021-03-08 00:02:15
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,779
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26866348
Author URL: https://archiveofourown.org/users/CanineR7A7/pseuds/CanineR7A7
Summary: After being the one to strike the killing blow, Nagisa is invited to attend U.A as a recommendation student. After spending the last year of his life training to become an assassin, how difficult could becoming a hero be?
Relationships: Akabane Karma/Shiota Nagisa, Midoriya Izuku/Shinsou Hitoshi
Comments: 15
Kudos: 265





	My Assassin Academia

**Author's Note:**

> I did not intend for this chapter to be this long.

If you had told Nagisa one year ago that he’d be training to become a hero he probably wouldn’t have believed it, then again, he hadn’t expected to spend a year training to become an assassin or that he’d actually manage to kill someone. But now, standing before the gates of U.A, he didn’t feel any of the insecurities that had plagued him last term.

“Um, excuse me?” He glanced to his side, mentally cursing himself for getting lost in thought so easily, noticing a green-haired boy dressed in the same uniform as him. Nagisa allowed himself to relax, smiling at the nervous-determination that painted the boy’s face.

“Hello, are you a first year too?” He greeted, smile widening when the boy nodded.

“Yeah, I’m Izuku Midoriya; it’s nice to meet you…?” Midoriya trailed off.

“Oh right, I’m Nagisa Shiota, please just call me Nagisa.” He introduced himself, watching as Midoriya seemed to think something over.

“Then just call me Izuku, it’s only fair.” Nagisa merely nodded his agreement, happy that he seemed to have made a friend already. The two of them headed into the main building, Nagisa barely managing to hide his excitement while his new friend practically sparkled with it.

“What class are you in?” He asked when he realised they’d headed down another hallway without splitting up, the green-haired boy blinked in confusion for a few moments, likely not noticing they seemed to be heading in the same direction.

“1-A, you?” Nagisa didn’t say anything though his smile gave it away if the way his new friend perked up was any indication. They didn’t say anything else as they searched for their class, deciding to wait until after school to get to know each other.

“Huh, think they couldn’t find a bigger door?” Izuku joked when they finally reached their class, Nagisa allowed himself a brief chuckle but didn’t say anything, as much as he’d loved his time in 3-E the old campus had much to be desired, he wasn’t going to start criticising his new school without good reason.

“Don’t put your feet on the desk!” The first thing the two of them saw upon entering the room was a boy wearing glasses arguing with another boy who kind of reminded Nagisa of Karma, the Karma before E Class anyway. He noticed that Izuku seemed to tense up when he saw them, were they old classmates? He made a mental note to ask about it later. He watched the glasses-wearing boy – Iida, as he introduced himself – approached Izuku and began apologising for something.

“Hey Nagisa, you made it in too?” His gaze snapped to the tall girl who he vaguely remembered seeing at the entrance exam, she was standing next to the boy with two-toned hair who he remembered coming in first. He was about to head over to her when a commotion at the door caught his attention, his hand automatically reaching for a knife that was no longer there as he turned to see what was going on.

“I’m your homeroom teacher, Shota Aizawa. Nice to meet you.” Nagisa found himself mentally comparing this teacher to his last one, it was hard not to considering everything that happened. There were a few obvious differences; where Korosensei had been jovial and practically bursting with energy at all times, Aizawa reminded him more of Mr. K – if Mr. K had taken to carrying a sleeping bag at all times that is.

“Put this on and go out onto the field.” Nagisa tuned out the responses of his classmates, easily slipping back into the no-nonsense mentality that Mr. K had encouraged during gym class. He slipped into a brief conversation with Izuku as they headed to the locker rooms, ignoring the glances when he followed the other boys; he was used to them at this point.

“Hey bro are you okay?” He glanced behind him, seeing a red-haired boy staring at him in concern. Oh right, he’d forgot about the scars.

“I’m fine.” Nagisa replied, expression easily morphing into the smile he usually wore. He sighed when the other boy didn’t seem convinced, quickly pulling on his gym shirt before awkwardly resting a hand on the taller boy’s shoulder.

“Really, I’m okay now.” The other boy still didn’t seem entirely convinced but Nagisa felt some of the tension bleeding out of his shoulders. He didn’t stick around long after that, he doubted their teacher would be too hard on them on the first day but he wasn’t taking his chances. He failed to notice the other two watching him as he left.

*-* *-* *-*

It didn’t really surprise him that he was the first one out, even back in E Class he’d always changed quickly. Aizawa didn’t say anything when he got to the field, though he did glance at him with something akin to approval, Nagisa decided to count that one as a win. It wasn’t too much longer before the others showed up, but their teacher thought otherwise if his facial expression was anything to go by.

“Quirk apprehension tests.” Nagisa only half-listened to his classmates’ comments while he considered his options. Sure, he and his class had been given permission to use their quirks all last year, but they hadn’t really used them that often, not even in gym class.

“Whoever comes in last place in all 8 tests will be judged to have no potential and will be punished with expulsion.” He swallowed around the lump beginning to form in his throat, sure he was fairly confident in his ability to control his quirk but it wasn’t exactly suited to anything remotely resembling a fitness test, combat? Yes, gym class? No. The expulsion threat certainly didn’t help matters, it wasn’t as though he didn’t have other options but he wasn’t planning on giving up that easily.

*-* *-* *-*

Test 1: 50-meter dash. Nagisa felt fairly confident with his performance; sure he’d never be a front-runner, that spot went to Iida easily. But his time fell somewhere in the middle rather than towards the end like he’d initially thought it would be. He idly noticed that Izuku hadn’t used his quirk either and found himself wondering whether it was because the boy’s quirk wouldn’t have been much help or if there was another reason behind it.

Test 2: grip strength. He did noticeably worse this time round, his time in 3-E left him with a much better endurance than most people his age but his overall strength hadn’t really improved all that much. He could’ve probably used his quirk but he didn’t see how it would’ve helped, Izuku hadn’t used his quirk either.

Test 3: standing long jump. He did reasonably well at that one, it didn’t feel anywhere near as good as jumping across rooftops or tree branches but it was familiar. He shared a brief grin with Izuku when the other boy walked over after his own less-successful attempt, once again trying to figure out what kind of power the green-haired boy possessed.

Test 4: repeated side steps. He didn’t do as well at that one, he was still more towards the centre of the group but he didn’t really feel as though he’d been quick enough. Izuku seemed to share the same thought about his own score.

Test 5: ball throw. Nagisa had been just as shocked as the rest of his classmates when the brunette – who reminded him slightly of Kayano – scored infinity, idly wondering where exactly the ball was going to land before stepping up to the plate himself. His throw paled in comparison though the time he’d spent helping Sugino train meant that it ended up going further than he’d initially thought it would. The real shock had been when Izuku took his turn, he felt his anxiety well up as he watched the confrontation between his new friend and their teacher – mind flashing back to gym class under Takaoka before he hurriedly shook it off, no, he wasn’t going to compare anyone to that man – he wasn’t sure what had been said between but the determination shining in his friend’s eyes gave him some idea. He watched as Izuku launched the ball into the air, gasping when he saw just how powerful his friend’s quirk was. His shock quickly melted into concern when he saw the state of the boy’s finger afterwards and made a mental note to ask him about it later.

Test 6: distance run. The next test wasn’t much different than the first but he felt much more confident about his results. Sure, he wasn’t the fastest runner in the world but this test wasn’t counting speed, it was counting endurance. He was only mildly surprised when he ended up in the top five.

Test 7: seated toe-touch & test 8: sit ups. He’d always been fairly flexible, years spent hiding from his mother when she was in one of her moods had seen to that. He wasn’t quite in lead but he wasn’t too worried about his overall placement, Izuku seemed to be struggling a bit but Nagisa didn’t really blame him, not with the current state of his hand.

*-* *-* *-*

“By the way, I was lying about the expulsion.” Nagisa definitely wasn’t the lowest scorer but it was still relieving to hear, and – as his eyes drifted to the bottom of the list – he knew Izuku was relieved to hear it too. He listened to the girl from his entrance exam mention that the lie was obvious but he wasn’t too sure.

“Midoriya, have the old lady fix you in the nurse’s office. Shiota, a word.” Nagisa winced at the use of his surname, sure he lived with his dad now but they hadn’t arranged a time to get it changed yet. He watched the others leave, sharing a reassuring smile with Izuku before turning his attention to their homeroom teacher.

“I’m sure you already know what this is about?” Nagisa grimaced at the question, he knew it would happen sooner or later, he’d just been hoping for the latter. He merely nodded in response, not entirely trusting his voice.

“As I’m sure you’re already aware, recommendation students are typically brought to our attention by individual heroes or organisations with close ties to them. A student being recommended by the Ministry of Defence is practically unheard of, you’re the first.” Nagisa didn’t say anything but he knew he wasn’t doing a particularly good job of hiding how he was feeling, the memories were still too raw and he hadn’t expected to be grilled about it this soon.

“Long story short, I looked at your file kid, even the parts the Principal was hesitant to share.” He remained silent, wanting to see what his new homeroom teacher was getting at before he tried to defend himself.

“Let me be clear here kid. What was asked of you, what you managed to achieve by the end of last year shouldn’t have happened.” Nagisa merely blinked in confusion, brow furrowing when his teacher only sighed in response.

“Don’t get me wrong, the fact that you were able to take down such a high-ranking villain with only a year’s worth of basic training is impressive, and I do want to see that potential with my own eyes. But you shouldn’t have been in that position, and that goes for all of your former classmates.” Nagisa merely nodded in acknowledgement, deciding it probably wasn’t worth mentioning that he’d do it all again if he had to, or that the rest of E-Class would the same in a heartbeat.

“I don’t know if you’re already seeing someone about any lasting trauma but I advise you speak to one of the councillors here, even if it’s just one conversation, is that fair?” Honestly? The last thing Nagisa wanted to do was burden anyone else with his problems, but Aizawa probably knew that already.

“Yes sensei.” He responded, finally trusting his voice enough to speak. Aizawa dismissed him then, Nagisa only managing a few steps before turning back to face his teacher.

“Oh er, could you call me by my first name? I don’t like people calling me Shiota.” If Aizawa was confused by the request he didn’t show it, merely nodding his consent before Nagisa ran off to re-join the rest of his class.

*-* *-* *-*

“Hey Nagisa.” He glanced up from where he was standing outside the nurse’s office, smiling when he caught site of Izuku. The boy seemed okay, the only evidence of his earlier injury being the bandage wrapped around his finger.

“Were you waiting long?” Nagisa chuckled softly as he shook his head, smiling when some of the tension bled out of his friend.

“No, are you okay?” He watched the other boy’s brow furrow in thought for a few seconds before realisation dawned on him.

“Oh that! Yeah I’m fine. My quirk, I’m not quite used to it yet.” Izuku trailed off, scratching the back of his neck in what Nagisa assumed to be embarrassment.

“Huh?” Not his greatest response but Izuku didn’t seem to mind.

“My quirk kind of came in late, as in ten years late.” Huh, that was odd, and explained a lot now that he thought about it.

“Do you know why?” Izuku merely shrugged, brow furrowing in thought.

“Not really. I started an intensive muscle workout towards the start of last year so I had a better chance of passing the entrance exam; the working theory is that I just put on enough muscle to handle it.” That kind of made sense, if it was breaking his bones now, Nagisa couldn’t imagine what it would’ve done to him as a child.

“What about you?” Nagisa’s brow furrowed in confusion for a few minutes before realising what he meant.

“Oh right, I didn’t use it earlier.” The two of them stopped in the hallway, Nagisa idly noticed that they’d almost reached the exit while they’d been talking.

“Oh, is it a non-combative quirk?” Nagisa merely shook his head, trying to figure out how to explain it without freaking him out. He was just about to reply when he heard his phone ring, quickly pulling it out of his pocket while sparing Izuku an apologetic glance.

_“Hey Nagisa.”_ Nagisa frowned in confusion when he realised who it was, sure he was living with his dad now but he was still getting used to being able to talk to him whenever he wanted.

“Hi Dad, what’s up?” He glanced up momentarily, smiling slightly when he saw Izuku had decided to wait for him.

_“I’m going to be a bit late today, why don’t you see if you can hang out with some of your friends?”_ Nagisa murmured a quick acknowledgement before ending the call.

“Sorry about that.” He apologised though it was clear Izuku didn’t mind, they’d just made it outside when another voice caught their attention.

“Hey guys!” The two of them glanced in the direction of the shout, Nagisa’s gaze instantly catching on the brunet and Iida from their class.

“Hi…” He trailed off sheepishly, the girl easily noticing what was wrong.

“Oh right, I’m Ochaco Uraraka.” She greeted, Nagisa once again found himself comparing her to Kayano before catching himself.

“Tenya Iida, a pleasure to meet you.” The boy re-introduced himself with a bow; Nagisa wasn’t really sure what to make of how formal he was but ultimately decided it didn’t really matter. He listened to his new friend stutter something about an insult when Uraraka guessed his name wrong and found himself mentally thanking whatever higher-being was out there that Nakamura and Karma weren’t here to see it.

“And you’re Nagisa Shiota right?” Uraraka addressed him.

“Yeah, please just call me Nagisa.” The two of them nodded their agreement though he noticed Iida was more hesitant. He was just about to ask if any of them wanted to hang out when another voice interrupted his thoughts.

“Oh hey Nagisa, I didn’t know you were still here.” He turned his gaze in the direction of the new voice, smiling when he caught sight of the tall girl from the recommendation exam.

“You’re Yaoyorozu right?” He asked, mentally chiding himself for not remembering. The girl didn’t seem to mind.

“You two know each other?” Uraraka asked, the two of them merely laughed in response.

“We met during the recommendation exam.” Nagisa answered, Yaoyorozu merely nodding in agreement.

“Oh, but you knew Deku before U.A. right?” It was Izuku who answered this time.

“No, we only just met today.” They spoke for a bit longer before Nagisa decided to ask if they were able to hang out. Iida took some convincing but they ultimately agreed.


End file.
